Lathes are used to cut veneer, in the form of a ribbon, from a wood log or block as the block is rotated. Typically lathes include an arrangement for rotating the wood block, a knife and a pressure bar, and may be either a spindle or spindleless type. In the spindle type there are two axially spaced head stocks that support the log and at least one head stock is driven for rotating the wood block. The spindleless type lathe typically has three parallel rollers that hold the wood block captive and at least one of such rollers is driven to rotate the block. In either type an adjustably movable knife is used to peel a ribbon of veneer from the block as the block is rotated. In any veneer forming apparatus the principal objective is to produce a ribbon of veneer that is of uniform and precise thickness.
Veneer must meet certain minimum quality standards and the thickness must be within a few thousands of an inch of the average. This precise thickness is necessary for the veneer to accept sufficient glue with a roll type spreader or to prevent panel rejection because of being too thin or to avoid excessive sanding losses. Veneer must be strong enough to avoid breakage during handling, and loose enough to be handled by automatic equipment, yet smooth enough to ensure proper glue distribution at the glue spreader. Multi layers of veneer are often laminated together to produce a panel product and uniformity of veneer thickness yields panels that are uniform.
The actual yield and quality of veneer is dependent upon lathe related variables, and as far as veneer quality is concerned, control is required for variable parameters such as smoothness, tightness and thickness variability.